Question 1012220
<pre>
From the graph below, it appears that the triangle is isosceles,
so all you need do is use the distance formula to find
 
(1) the length of MY
 and
(2) the length of AM

And they should be equal length, so MY and MA are congruent.  

{{{drawing(400,400,-2,5,-5,2,grid(1),

locate(1+.05,1+.3,"Y(1,1)"), locate(4+.05,-4+.3,"M(4,-4)"),
locate(-2,-1+.3,"A(-1,-1)"),
line(1,1,4,-4),line(4,-4,-1,-1), line(-1,-1,1,1) )}}}

Edwin</pre>